Nah, If you don´t go back longer than 1979, they actually offered 1 year visa already. I assume you don´t go back longer than 1987, as you are talking about 30 day monthly runs, as that kind of visa/permission to stay was not available before that time.
Nah, Immigration looked at your passport. The nationality was available on the first page, so they did not need to ask you.
With todays over population and mass tourism, that would only lead to more accidents.
Actually, I did only get a stamp in my passport. Everybody else gave me a wai.
Regarding missing the bus, you didn´t need to worry too much about that either. In many cases they waved the fine for only a day or a couple of them. Otherwise I think it was still 200 a day and no problem at all.